Hard alloys



Patented June 18,1946

' man ALLOYS Roy B. McCauley, Chicago Heights, Ill.

No Drawing. Application January 20, 1945,

, Serial No. 573,805

' 4 Claims. (01. 75-125) This invention relates to hard ferrousphosphide alloys characterized by high abrasion resistance as well ascorrosion resistance.

This application is a continuation-in-part of my application Serial No.476,965, filed February 24; 1943.

7 It is the object of the present invention to pro-- vide hard corrosionand abrasion-resistant phosphide alloys having a comparatively lowphosphorus content with a disembrittling metal con-- tent consisting ofchromium together with small proportions of grain refining metalsconsisting of copper and nickel in substantially identical quantities.The small quantities of the latter metals which are embodied in thealloys of the present invention permit a maximum output of these alloysfor industrial uses despite the restrictive allotment of these metals atthe present time.

I have found that the alloys in accordance with the present inventiondisplay an extremely permanent hardness without heat treatment. In

' fact, while the hardness may be critically controlled by theingredients of the composition, the same remains unaffected by any heattreatments.

It is the object of the presentinvention to obtain tough, and hardferrous alloys having a high degree of resistance to physicaldeteriorating influences as well as corrosion resistance which isparticularly marked against oxidizing acids and brines oi the characterof nitric acid and nitrates.

The properties of the alloys in accordance with the present inventionrender it particularly useful in the production of cast parts of pumpsemployed for handling, abrasive materials in subdivided iorm; productionof the alloy in the form oi welding rod, strip, powder or other physicalform to .be fused into union with surfaces to protect them againstabrasive influences, for example, in cases of valves, valve seats,pump-rods, knives, pulverizing hammers, etc.; also centrifugally castliners or surfaces for tubes or pipes.

These alloys are very active and alloy with other metals or alloys inthe molten state, so that soft inserts needed in castings may beanchored by alloying with the cast alloys in accordance with thepresent'invention and special insert shapes for anchors will bethereby'rendered unnecessary.

The invention resides in a complex alloy of iron and phosphoruscontaining varying amounts .of

chromium and grain refining elements such as.

copper and nickel and in which any other elements such as-carbon, all incombined form, silicon, sulphur, manganese and aluminum may be presentas impurities in quantities less than 1.00%

'since the elimination of suchfrom the alloy would prove too costlyafter these elements are introduced into the alloy as a result of theirpresence in the-scrap metal from whichthe alloy may be compounded. Theadvantageous results of the present invention are attainable 'by analloy having the following essential ingredients therein. within theranges indicated in addition to iron. v

Percent Chromium; From 10.00 to30.00 Phosphorus 'From 0.75 to less than5.00 Coppers .From 0.50 to less than 5.00 Nickel; From 0.50 to less than5.00

The iron and phosphorus are combined under circumstances that leaveunoxidized phosphorus to react upon the iron with the result thatironphosphide is formed, expressed by the symbol FesP. When the phosphorusis in a ratio as much as 1.70% to the iron, the mass 01' iron will besaturated with iron phosphide (FeaP). Increase of phosphorus up to 10.2%brings a eutectic alloy into existence consisting of the saturated solidsolution FeaP distributed through the solid solution.Further-increase'of proportion of phosphorusup to 15.58% results in abody composed of the iron-phosphide plates surrounded by the eutecticalloy. Increase of the phosphorus materially above 15.58% fills thegrain boundaries with iron phosphide and causes the whole alloy to existas a compound.

As is generally known, combining phosphorus with iron undercircumstances to produce iron phosphide produces a body which, while,highly resistant to chemical deterioration, is too brittle the grain ofthe chromium iron phosphorus alloy.

The use with copper of a grain refiner such as nickel has the functionof promoting the solution of copper in iron.

My Patent No. 2,261,174, issued November 4, 1941, described theproduction of chemically resistant and physically strong quaternaryalloys by combining 1.70%. to 25.0% phosphorus with 29.0% to 75.0% ofiron in a manner to produce iron phosphide; adding to the alloy in amanner to also convert it into its phosphide, from 1% to 19% of adisembrittling metal which is one of the metals nickel, cobalt, copper,molybdenum and tungsten; and finally adding, in a manner to convert itinto its phosphide, from 1% to 19% of a grain refining corrective metalwhich is not one of the disembrittling metals used but is one of themetals tin, mangenese, molybdenum, tungsten and vanadium, variance ofphosphorus being provided for directly to correspond with the severityof corrosive environment in which the alloy is to be used.

One feature wherein the present invention differs from the quotedinvention heretofore patented to me is that I have now discovered thatby the use of relatively low proportions of disembrittling metal hereinset forth, and particularly if the proportions of these two metals bekept closely alike, I get wholly unexpected results, in that whereas mypatented formulae are the result of research aiming to producequaternary alloys having high corrosion resistance, my present inventionproducesalloys all of which contain chromium and are hard or abrasiveresistant; a collateral attribute of the present invention is thatvariation of proportions of which I call the disembrittllng grainrefining elements can be regulated to a point to define a complete rangeof Rockwell hardness, to-wit: Rockwell hardness varying all the way fromhard formulas that cannot be machined at all and finished only bygrinding, to those that are soft enough to be machined, yet theseabrasion resistant metals will all be corrosion resistant as well. Theconditions are remarkable in that they are arrived at largely byradically small variations in the percentages of thedisembrittling andgrain refining elements of copper and nickel, and by maintaining theproportions of these two metals closely the same.

The following series of formulae which may be grouped as coming withinthe herein recited general formula of the present invention illustratethe radical change in R/C hardness obtainable from a comparatively smallchange in corrective metal range:

a An alioyenibodying the present invention in the range of R/C test of50 to 59 is:

Cr' 18.00 C11 1.00 Ni 1.10 P 5.00 Fe Balance An alloy embodying thepresent invention inthe range of R/C test of 40 to 49 is:

Cr 18.50 C" 1.00 Ni 1.10 P 4.00

Balance 4 An alloy embodying the present invention in the range of R/Ctest of 30 to 39 is:

Cr 22.00 Cu .50 Ni .50 P 2.00 Fe Balance An alloy embodying the presentinvention in the solutions of nitric acid, nitrates or brine. It can becast in parts requiring a great deal of machining as it has a Rockwellhardness of from 20 to 30, C scale.

The type C alloy, which is slightly harder, is of the followingcomposition:

Cr About 21.50 to 22.00 Cu About .25 to .50 Ni About .25 to .50 P About1.75 to 2.25 Fe-.. Balance The hardness of this alloy ranges from 30 to40 Rockwell, C scale, and machining of parts made therefrom is usuallyaccomplished by using a carbide tool.

The iron phosphide alloys disclosed above containing a substantialamount of chromium with low phosphorus, nickel and copper contents, eachbelow an upper limit of 5% produce a group of hard, tough, corrosionresistant and abrasion resistant alloys which have proven to be a markedadvancement in the field of ferrous phosphide alloys known heretofore.

I claim:

l. A hard tough corrosion and abrasion resistant ferrous phosphide alloyrequiring no heat treatment to develop its desirable properties andhaving a low phosphorus, nickel and copper content, each beiow an upperlimit of 5% and including chromium in an amount of 10.00% to 30.00%.phosphorus from 0.75% up to its upper limit and substantially identicalquantities of each of copper and nickel from 0.50% to their upperlimits, the remainder being iron with other ingredients such as carbon,silicon and other elements being present as impurities in quantitiesless than 1.00%

2. A hard tough corrosion and abrasion resistant ferrous phosphide alloyrequiring no heat treatment to develop its desirable properties andhaving a low phosphorus, nickel and copper content, comprising chromiumfrom about 25% to 26%, phosphorus from 1.75% to 2.75% and substantiallyidentical quantities of each of copper and nickel from 0.50% to 0.75%,the: remainder treatment to develop its desirable properties and havinga low phosphorus, nickel and copper content comprising chromium i'romabout 21.50% to 22.00%, Phosphorus from about 1.75% to 2.25%.

copper from about 0.25% to 0.50% and nickel 5 from about 0.25% to 0.50%.the remainder being iron with other ingredients such as carbon, siliconand other elements being present as impurities in quantities less than1.00%.

. 4. A hard tough corrosion and abrasion resistl0 ingredients such ascombined carbon, silicon and.

other elements being present as impurities quantities less than 1.00%. l

' ROY B. MOCAULEY.

